Superlative form of quiet; the most silent or making the least amount of noise.
From Latin 'quietus' (peaceful, at rest); 'quiet' entered Middle English from Old French, and the superlative '-est' form has been used since Old English.
Silence was once a scarce commodity, but in modern life it's become nearly extinct—neuroscience shows that complete silence actually makes people uncomfortable because our brains crave minimal stimulation.
Complete word intelligence in one call. Free tier — 50 lookups/day.